In the past, it has been exceedingly difficult to reprogram firmwares associated with field-deployed devices. These firmwares contain data and programs to perform a variety of tasks, including controlling a plurality of output devices in response to a plurality of input devices. The firmware data and programs, hereafter generically referred to as “firmware”, are typically stored in a non-volatile memory (NVM) contained in each device. Periodically, it is necessary or desirable to upgrade the firmware of each device in order to fix bugs or to improve the performance thereof.
Several methods were devised in the past to upgrade firmware. One conventional method is that the firmware provider sends the user (or field service personnel) a new NVM containing the upgraded firmware. To perform the firmware upgrade, the old NVM which stores the previous firmware is physically removed (unplugged) from the processor module and replaced with the new NVM containing the upgraded firmware. A typical NVM used in such a scenario is one-time programmable read-only memory (ROM).
A first drawback to this method is that it is causes an undesirable transportation delay. The transportation delay is caused by the fact that the new ROM is a physical unit, which must be transported from the firmware provider up to the field-deployed device. These delays are often extremely expensive and inconvenient for users, especially if devices are taken out of operation pending the arrival of the firmware upgrade.
A second drawback to the above-mentioned method is that it is hardware intensive. Typically, the device must be physically removed from its casing and the ROM must be replaced manually. Although this approach may initially appear simple, replacing the ROM may not be the best solution in many circumstances. For instance, sockets are expensive and are often the source of reliability problems. Conversely, the removal of through-hole ROM chips that have been soldered into a board can be time consuming and difficult. If surface mount packaging is used, then specialized equipment is needed to replace the parts. Yet, even with an experienced person doing the de-soldering, there are always the risks that the whole board be ruined accidentally. Furthermore, if foundry ROM programmed-at-the-mask level is used, then there is the additional issue of the lead-time required to obtain the newer version of the parts.
A third drawback of the conventional method is that it requires additional hardware, namely the NVM itself. The firmware provider must typically incur the additional cost of providing, programming and shipping the new NVM for the purpose of performing the upgrade. Additionally, if the firmware provider does not have any NVM available when the user requests an upgrade, then the user must wait an additional period of time before the upgrade can be performed.
Another method is to replace the ROM type NVM with an electrically erasable and re-programmable, more particularly an alterable non-volatile random access memory, for instance EEPROM (electrically erasable programmable read-only memory) or Flash memory, and store the firmware therein. Conventional methods used hitherto using such memories typically include a separate interface to the field device, such as a serial port or similar access arrangement, for downloading information. For instance, U.S. Pat. No. 5,566,335 to Nash et al. teaches such a method. The EEPROM memory is generally divided in 16 kB blocks that can each hold a new version of the firmware, in effect multiplying the memory requirements for an upgradable device. U.S. Pat. No. 5,878,256 to Bealkowski et al. teaches a similar method for upgrading the BIOS firmware on personal computers.
These methods are frequently not suitable, as they generally require an operator to go near the field-deployed device in order to connect a downloading device, such as a personal computer or another programming apparatus. The operation must be repeated for each device to be upgraded. This task is thus very tedious and time consuming. It is consequently a very expensive way of achieving the necessary reprogramming of field-deployed devices. A further drawback is that on-site re-programming is often not possible because of the location of many field-deployed devices. Furthermore, the devices may be enclosed in outdoor housings which would need to be opened to access the download connection. Such openings of the housings are undesirable as adverse weather conditions can wreak havoc with the delicate electronics utilized therein.
Another possible method is to reprogram memories remotely via a network link, thereby eliminating transport delays and most, if not all, hardware manipulations. For instance, U.S. Pat. No. 6,055,632 to Deegan et al. teaches how to reprogram NVM via an Ethernet connection linking a personal computer to a communication daughter board interfaced to the device's motherboard. The firmware upgrade is downloaded to the daughter board's dual port random access memory (RAM). The daughter board then reprograms the Flash NVM from its dual port RAM. U.S. Pat. No. 6,055,633 to Schrier et al. teaches how to reprogram memories in field devices over a power communications link, by further controlling the amount of current the device under upgrade draws in the process. This method requires doubling the memory requirements because the new firmware is stored in a temporary memory area reserved for new applications. The upper memory is utilized to accept new firmware during download operations. The lower memory contains the normal, or currently running firmware. U.S. Pat. No. 5,937,198 to Nelson et al. teaches a method of remote Flash memory reprogramming that uses techniques of temporary RAM buffering and program execution as it replaces the old firmware with the upgrade. U.S. Pat. No. 5,623,604 to Russell et al. and U.S. Pat. No. 5,467,286 to Pyle et al. teach how to remotely alter firmware using similar means, by which the upgrade is first stored to RAM before being loaded in the NVM.
Although the above-cited patents teach various methods of upgrading firmware via a network link, they involve doubling memory requirements to hold the old and new versions of the firmware at a given time during the process, thus adding costs to the devices.